Auxiliary mechanical spool valves GPA20 and GPA40 rear axles -Spool valve assembly


Preliminary operation
Disconnect the spool valve control cables.

Removing the spool valves 


The spool valve block assembly must be removed complete.
Locate and disconnect the electrical connectors.
Locate and disconnect the hydraulic pipe(s) fitted to the spool valves and couplers. Remove support plate A. Remove the spool valve block.

Removing the lift control spool valve
Remove the differential lock support. Place the assembly on a table. Separate the spool valve blocks. The linkage spool valve is located in the middle of the spool valve block.

Removing the inlet block 
Remove the differential lock support. Place the assembly on a table.
Remove the inlet block.


Install the spool valves
Wipe clean the mating faces of the inlet block, the lift control spool valve, the auxiliary spool valves and the end plate. Check that each element is perfectly flat. Check the tightness of the studs on the inlet block.
Place new seals (3) (4) (5) on each component of the spool valves).


Reassemble the spool valve block on the workbench, following the assembly instructions. Reinstall the complete block on the tractor.
Install the hydraulic pipes to the spool valves and couplers according to the positions identified during the removal.
Reconnect the lifting and lowering solenoid valves according to the positions identified during the removal.

Install and adjust control cables. Start the engine.
At each position, check the operation:
- of the hydraulic system.
- of the electronic system.
Check the oil tightness of the spool valves and hydraulic unions.

Assembly procedure

To obtain a correct assembly of the seals (3) (4) (5), the spool valve block must imperatively be assembled vertically.


Final assembly
Partially tighten the nuts in contact with the end plate.
Place the distribution block with the F faces on a flat surface to ensure correct alignment of the attachment points.


Tighten the nuts (8) of the end plate (6) to a torque of 30 - 33 Nm.
Correctly fit the spool valve block on support S. Install and tighten the screws (10).



Installing and adjusting the control cables




Special points

- The pins (2) must be fitted with the threads slightly smeared with Loctite 241 or equivalent.

- Figures 1 to 3 in the dark circles show the assembly order of the levers which control the spool valves.

- The fitting of a fourth control lever is provided for on the cab console. It will be placed to the left of lever 1 (viewed from the driver's seat).

- The friction washers (1) are smeared with molybdenum sulphide grease before assembly.

- The nuts (3) must be tightened so as to obtain a slight resistance for the levers during operation.

On support (6) and lever 

Depending on the type of spool valve, the clevis (4) may be fitted on link A or B:
- assembly Install A: normal spool valves;
- assembly Install B: spool valves with floating position.




Pass the cable through the flange (9) located at the rear right of the cab and then through the stirrup (8). The hole in stirrup (8) is eccentric. To Install a control for a spool valve with a floating position, this hole must be at the top so as to correctly align the cable and its fastening.


Screw the clevis (4) flush with the threaded part of the cable (7) and Install it on link A or B of the lever concerned. Position clip (5). Tighten the nut on the clevis and check that the cable is not constrained in any way.

On the spool valves 
Without turning the main spool valves half a turn, check that they are in the neutral position. Screw the clevis (1) so that it is flush with the threaded part of the cable (7). Tighten nut (3). Fit the pin (4).


Partially remove the bell housing (5). Install the screws (6) without tightening them. Turn and adjust the tubular cover in order to correctly centre the control lever in the slot specially provided on the console.
Lock the screws (6). Tighten the nut (2) to a torque of 20 Nm.
Check the correct operation of the spool valve controls in all three or four positions, depending on the type.